The present invention relates to a large size projection television set in which projection light rays from CRT units are focused on a screen. The present invention also relates to a large size projection television set in which projection light rays from projectors such as CRT units are focused on a screen by reflecting the light rays at reflectors. The present invention also relates to a projection television set provided at a front face of a body casing with a screen assembly having a coupling means.
Recently, a large size projection television set has been proposed in which a plurality of CRT units are arranged up and down and right and left and projection light rays from the respective CRT units are focused on a screen.
More specifically, as shown in FIG. 1, the conventional projection television set P.sub.0 has an integrally formed body casing 50, and a large size screen S.sub.0 is provided at a front face of the body casing.
For instance, such a large size projection television set is very large to be 1 m 80 cm wide (W), 2 m high (H) and 75 cm deep (D). In particular, if its width exceeds 1 m 80 cm, it would be impossible to load it into a regular elevator when the TV set is transported to a site after the inspection of a factory. Thus, the transportion to the site is very complicated and the place where the TV set is to be laid is unduly limited. These problems would limit the sales market and its flexibility. On the other hand, in the case where the body is exploded or dismounted into a screen, CRTs, mirrors, electric components and the like which are to be transported to the setting place and to be assembled in the place, the assembling work and the adjustment work would be time-consuming. In addition, in this case, some other adjustment and measurement instruments have to be transported together, resulting in further complication in work.
In view of the foregoing shortcomings, an object of the present invention is to provide a projection television set which may readily be transported and assembled.
Recently, a large size projection television set has been proposed in which a plurality of CRT units are arranged up and down and right and left and projection light rays from the respective CRT units including projection lenses are focused on a large-size screen by reflecting the light rays by reflectors.
More specifically, as shown in FIGS. 2 and 3, the conventional projection television set P.sub.0 has a casing 50 with a rectangular cross-section. The casing 50 is partitioned into an upper unit 51 and a lower unit 52. In the upper and lower units 51 and 52, upper and lower CRT units 53 and 54 having upper and lower mirrors 55 and 56 symmetrically arranged with respect to a horizontal line l are located corresponding to the associated mirrors 55 and 56, respectively. The upper CRT unit 53 is disposed within an upper reception space 60 in the vicinity of an upper end of a screen S.sub.0 provided at a front face of the casing 50, whereas the lower CRT unit 54 is disposed at a position in the vicinity of a lower edge of the screen S.sub.O of the lower unit 52.
However, in the case where the upper CRT unit 53 and the lower CRT unit 54 as well as the associated upper and lower mirrors 55 and 56 are thus arranged, assuming that a size of the screen be of 80 inches, the depth W is reduced to, for example, 620 mm but the height H of the casing 50 would reach, for example, 2,350 mm since the upper CRT unit 53 is disposed in the upper reception space 60. If the height thereof would be extremely increased, in the case where the projection television set P.sub.0 is installed within a building, not only would it be physically impossible to install the television set in an omnifarious building having an average interior height of 2.2 m up to the ceiling but also it would be impossible to load the television set into an elevator for installation thereof into the building. The transportation of the television set is also inconvenient.
Accordingly, in view of the above-noted defects, an object of the present invention is also to provide a projection television set which has a relatively low height in spite of a large size screen and which may be conveniently transportated.
On the other hand, in general, in projection television sets, CRT units, LCD units and the like are provided in a body casing, and a screen assembly which is formed by combining a lenticular sheet and a Fresnel lens is mounted on a front face of the body casing. The screen assembly is of a type in which the screen assembly may be inserted in the front face of the body casing at the site. The screen assembly may be removed away from the body casing for cleaning the interior of the body casing or for adjusting a focus of lenses of the CRT units.
However, the recent projection television sets have been enlarged. When their sizes of the screens are of about 50 inches, the weights thereof would not seriously cause problems. Nevertheless, when the projection television sets use large screens of 80 inches, the weights would reach 50 kg, and it would be difficult for one worker to remove the screen assemblies from the body casings for cleaning reflector mirrors, screens and the like. This would be inconvenient. Also, in the case where the screen assembly is transported separately, it is time-consuming to mount the screen assembly in place by using screws.
In view of the foregoing defects, an object of the invention is to provide a projection television set in which a body casing interior may readily be opened upon the cleaning operation, the lens focus adjustment and other maintenance operation after the installation of the television set and in which it is easy to carry out various operations.